1. Field of the Invention
The present invention relates to vinyl ether compounds that are useful as raw materials for pharmaceutical drugs, agricultural chemicals, and polymers, as well as to processes for producing such vinyl ether compounds.
2. Description of the Related Art
Vinyl ether compounds are useful as raw materials for pharmaceutical drugs, agricultural chemicals, and other fine chemicals and as raw materials for polymers such as resist resins, optical plastics, transparent resins, and crosslinking resins. Among them, vinyl ether compounds each having an alicyclic skeleton, a lactone skeleton, or another non-aromatic cyclic skeleton are promising material monomers for resist resins, since they can improve transparency and resistance to dry etching when they are used as comonomers of such polymers. Vinyl ether compounds each having plural vinyl groups are suitable as material monomers for crosslinking resins, since they can impart high solvent resistance to the resulting polymers. In addition, such vinyl ether compounds develop odor and irritate the skin less than acrylic compounds and are excellent in handleability and workability. However, there are less types of vinyl ether compounds at higher cost than acrylic compounds (monomers) on the market, which do not sufficiently fill the needs for such vinyl ether compounds.
The vinyl ether compounds have been prepared, for example, by a process in which acetylene is allowed to react with an alcohol by catalysis of an alkali metal hydroxide or an alkali metal alcoholate. However, this process is disadvantageous in that it uses acetylene that is difficult to handle. Alternatively, U.S. Pat. No. 2,579,411 discloses a process for producing a vinyl ether compound, in which an alcohol is allowed to react with a vinyl ester in the presence of a mercury salt of a strong acid at a temperature of from −75° C. to −15° C. However, this process requires the use of highly toxic mercury, needs a reaction at very low temperatures, and is not suitable as a process for commercial production.